Season the chicken pieces with salt, black pepper, and Italian seasoning.

Heat the olive oil and butter in a large skillet over medium-high heat. Add the chicken and cook for 5 to 7 minutes, stirring occasionally, until golden brown and cooked through. Transfer the chicken to a plate.

In the same skillet, add the onion and cook for 2 to 3 minutes until softened. Stir in the garlic and red pepper flakes, if using, and cook for 30 seconds until fragrant.

Pour in the chicken broth, heavy cream, lemon juice, and lemon zest, scraping up any browned bits from the bottom of the pan.

Add the gnocchi and bring the mixture to a gentle simmer. Cook for 4 to 5 minutes, stirring occasionally, until the gnocchi is tender and the sauce has slightly thickened.

Stir in the Parmesan cheese and baby spinach. Cook for 1 to 2 minutes until the spinach wilts and the sauce becomes creamy.

Return the cooked chicken to the skillet and stir to combine. Taste and adjust seasoning if needed.

Remove from heat, garnish with fresh parsley, and serve warm.